Lubricating grease



United States Patent 3,159,090 LUBRICATING onnasn Norman R. Odell, Wappingers Falls, and Joseph F.

This invention relates to a novel class of compounds having special utility as grease thickening agents. More particularly, it relates to a class of aminobenzoic acid derivatives and to lubricating greases prepared from such compounds.

The compounds contemplated by this invention are p- (N-carboalkoxy)aminobenzoic acids, and the metal salts thereof. The metal salts are represented by the formula wherein R is an aliphatic hydrocarbon group, M is a metal, such as sodium, potassium, lithium, calcium, barium, strontium, zinc, aluminum, tin, cadmium, iron manganese, etc., and n is an integer equal to the valence of M.

The preferred compounds of this class are those wherein R contains from 1 to about 30 carbon atoms, and most suitably from about 8 to about 22 carbon atoms, and M is a metal of the group consisting of alkali metals, alkaline earth metals, aluminum and zinc.

The above compounds are obtained by employing well known reactions, such as by reacting a chloroformic acid ester and aminobenzoic acid in the presence of a solvent such as pyridine. The reaction products are converted into the metal salts by reaction with suitable basic metal compounds in the conventional manner.

We have found that the p-(N-carboalkoxy)amino- .benzo'ic acid metal salts constitute a very valuable class of grease thickening agents. Greases thickened by these compounds are characterized by a combination of high dropping points and excellent stability, not obtainable with the conventional grease thickening agents or with other N-organo substituted aminobenzoic acid salts which have been employed as grease thickening agents heretofore.

The greases of this invention comprise essentially oleaginous liquids admixed with metal salts of the above class in sufiicient amounts to thicken the oleaginous liquids to a grease consistency. Ordinarily, the composition will contain from about to about 45 percent by weight of the thickening agent, and preferably from about to about 35 percent by weight of the metal compound based on the weight of the composition.

The oleaginous liquids employed in these greases may be any oils of lubricating characteristics which are suitable for use in the conventional soap thickened greases.

They include particularly the conventional mineral oils in the lubricating oil viscosity range, having viscosities from about'80 seconds Saybolt Universal at 100 F. to about 225 seconds Saybolt Universal at 210 R, which may be either distillate or residual fractions, and parafiinc or naphthenic in character. The preferred mineral oils are those having viscosities in the range from about 300 seconds to about 600 seconds Saybolt Universal at 100 R, which may be blends of different oils including oils of lighter and heavier viscosities. For special purposes, such as for producing wide temperature range greases, synthethic oils, such as polyethers, polyesters, silicone oils, etc. may be employed as part or all of the oleaginous liquid component.

Suitable polyester oils include the aliphatic dicarboxylic acid diesters such as, for example, di-Z-ethylhexyl seba- 3,150,090 Patented Sept. 22, 1964 cate, di(secondary amyl) sebacate, di-Z-ethylhexyl azelate, di-isooctyl adipate, etc. A particularly suitable class of synthetic polyester oils are those disclosed by R. T. Sanderson in US. 2,628,974, obtained by reacting dibasic aliphatic acids with glycols and end-blocking the reaction products with monohydric aliphatic alcohols or monocarboxylic aliphatic acids. The preferred materials of this character are products obtained by reacting monoor polyalkylene glycols with dicarboxylic acids and monohydric alcohols, represented by the formula wherein R is an aliphatic hydrocarbon or an aliphatic ether group containing from 4 to 12 carbon atoms, R and R are aliphatic hydrocarbon groups containing from 1 to 12 carbon atoms and x is an integer from 1 to 5.

Suitable silicone oils are described, for example, in US. 2,410,346 and US. 2,469,888. The methylchlorophenyl silicone oils, containing at least about 3 percent by weight of chlorine, and ordinarily about 4-12 percent by weight of chlorine, are regarded as the preferred silicone oils for use in the greases of this invention.

Additives of the usual types employed in lubricating greases may be employed in these greases also, including oxidation inhibitors, rust and corrosion inhibitors, extreme pressure agents, etc. A very suitable class of oxidation inhibitors are those of the amine type, including for example, diphenylamine, alphaand beta-naphthylamines, diphenyl-p-phenylenediamine, and polymerized dihydroquinolines, such as 2,2,4-trimethyl-1,2-dihydroquinoline, which is sold commercially under the trade name of Agerite Resin D. Such materials may be employed suitably in amounts from about 0.05 to about 10 percent by weight, and preferably in amounts from about 0.5 to about 5 percent by weight of the grease composition.

The grease preparation may be carried out by merely mixing together the preformed metal compound with the lubricating oil and any additives employed in the grease, employing any convenient means such as milling in a colloid mill or a paint mill to obtain a thorough dispersion of the thickening agent in the oleaginous liquid. The preparation may also be carried out by an in situ method if desired, wherein the benzoic acid derivative is neutralized by means of a basic metal compound in the presence of at least a portion of the lubricating oil employed in the grease.

The following examples are given for the purpose of more fully disclosing the invention:

EXAMPLE I Para-(N-carbododecyloxy)aminobenzoic acid is prepared in the following manner: 137 grams of p-aminobenzoic acid is added to 248 grams of lauryl chloroformate with stirring, 200 milliliters of pyridine then added slowly, the mixture refluxed for minutes and allowed to stand for several hours. The reaction product is separated by diluting the reaction mass with cold water and filtering. The filter cake is washed with Water, recrystallized from acetone and air dried. The product is obtained in about 79.7 percent yield. it has a saponification number of 170, as compared with the theoretical value of 160.6.

XAMPLE II A lubricating grease having the following composition in percent by Weight:

Sodium p-(N-carbododecyloxy) 8.1 Mineral lubricating oil 91.9

The p-(N-carbodod ecyloxy) aminobenzoic acid employed as the saponifiable material is obtained as described in Example I.

The mineral lubricating oil is a refined naphthenic distillate oil having a Saybolt Universal viscosity at 100 F. of about 315 seconds.

The grease preparation is carried out in the following .manner: 150 grams of p-(N-carbododecyloxy)aminobenzoic acid obtained as described above are charged to a grease kettle together with 300 grams of mineral lubrieating oil and 36.2 grams of 50.4 percent aqueous sodium hydroxide solution and the mixture heated at 180190 F. for 2 hours to complete the reaction. The mixture is then heated further at 3l3320 F. for 2 hours to dehydrate, and thereafter cooled with continued stirring at a rate of about 1 F. per minute, while adding an additional 1,715 grams of mineral lubricating oil. The grease is drawn at about 136 F. and finished by milling with ,2 passes through a Premier Colloid Mill at 0.002 inch clearance.

A smooth N.L.G.I. No. 3 grade grease of buttery texture is obtained as described above. It has a dropping point above 500 F. and good shear stability as shown by the following results obtained in the ASTM Worker Test:

Penetration at 77 F. A cone):

Unworked 260 Worked, 60 strokes 253 Worked, 100,000 strokes 236 EXAMPLE III A lubricating grease having the following composition in percent by weight:

Sodium p-(N-carbododecyloxy)aminobenzoate 12.6 Diphenylparaphenylenediamine 1.0 Sarkosyl LC 1.0

Synthetic ester oil 85.4

The p-(N-carbododecyloxy)aminobenzoic acid is obtained as described in Example I.

The synthetic ester oil is obtained reacting sebacic acid, 2-ethylhexane-1,3-diol and Z-ethylhexanol in about 2:1:2

ratio respectively, and consists predominately of the compound The grease preparation is carried out substantially as described in Example I, employing the above materials in the indicated proportions by weight, except that the salt is formed before mixing it with the lubricating oil and the milling is omitted. V

A smooth N.L.G.l. No. 2 grade grease of buttery texture is obtained as described above, having a very high dropping point and other superior lubricating properties as shown by the data given in Table 1 below, which were obtained upon this grease in standard tests. Comparative data are also given for a grease thickened with 21.1 percent by weight of sodium N-octadecylterephthalamate, being of the same composition otherwise.

Table l Na-oetadec- Example ylterephth- II alamate thickened grease Penetration at 77 1?. ($4 cone)- Unworked a 272 Worked, 60 strokes 287 264 Worked, 100,000 strokcs 2&7 Dropping Point, IL; 576 501 ASTM Bomb Oxidation Test; (100 hrs. at

21091 Pressure drp,lbs 3 19 1 Dynamic Water Resistance Test loss, percent. 0

- Water Absorption Test:

Water absorbed, percent 80 70 Penetration of emulsion 309 268 Oil Separation Test hrs. at 350 F.): Oil

separated, percent 2.5 16. 7 -GRC Bearing Protection Test Rating Pass Fail Cit As shown by the data, the above grease of our invention had a very high dropping point, in addition to shear stability and excellent oxidation and water resistance properties. It was unexpectedly very much superior to terephthalamate thickened greases both in yield and in lubricating properties, particularly in its superior oxidation resistance and stability against oil separation.

In addition, the p (N carboalkoxy) aminobenzoate thickened greases were unexpectedly much superior to greases thickened with p-(N-acyl)aminobenzoates, both in yield and in their greatly improved storage stability. Table II below shows the unworked penetrations after storage for a grease thickened with 8 percent by weight of sodium p-(N-carbododecyloxy)aminobenzoate in com parison with that of a grease of the same grade thickened with 15.9 percent by weight of sodium p-(N-octadecyl)- aminobenzoate. Bothgreases were otherwise of the same composition as the grease of Example 11, and were prepared in substantially the same manner except that they were finished by milling with 2 passes through a Premier Col oid Mill at 0.002 inch clearance.

EXAMPLE IV A lubricating grease having the following composition in percent by weight:

Barium p-(N-carbododecyloxy)aminobenzoate 18.3 Diphenylparaphenyldiamine 1.0 Synthetic ester-mineral oil blend 80.7

The barium p-(N-carbododecyloxy)aminobenzoic acid is obtained as described in Example I.

The lubricating oil is a blend of di-Z-ethylhexyl sebacate and a refined parai'finic distillate oil having a Saybolt Universal viscosity at F. of about 100 seconds, in a ratio of 3:1 respectively by weight.

The grease preparation is carried out by neutralizing the p-(N-carbododecyloxy)aminobenzoic acid with barium hydroxide in the presence of mineral lubricating oil employed in the grease, employing a mol ratio of acid to barium hydroxide of 2:1, respectively, dehydrating at a higher temperature and adding the remainder of the lubricating oil during cooling as described in Example II.

A smooth N.L.G.I. No. 2 grade grease is obtained as described above having a dropping point above 500 F. and very good lubricating properties generally, including good oxidation resistance and very superior stability in the presence of water.

As shown by the data given above, the p-(N-carboaikoxy)arninobenzoie acid metal salts produce lubricating greases having exceptionally high dropping points as well as superior lubricating properties generally. They are unexpectedly superior to salts ofother amidobenzoic acid compounds such as the terephthalamates and p-(N-acyl)- aminobenzoates for this purpose. e

The aminobenzoic acid derivatives disclosed herein are claimed in our copending application Serial No. 783,132,

now abandoned, filed December 29, 1958, of which the present application is a division.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as .are in icated the appended claims.

5 We claim: 1. A lubricating grease consisting essentially of a lubricating oil thickened to a grease consistency with a compound represented by the formula where R is an aliphatic hydrocarbon group containing from 1 to about 30 carbon atoms, M is a metal and n. is an integer equal to the valence of the said metal.

2. The grease according to claim 1 wherein M is an alkali metal.

3. The grease according to claim 1 where M is an alkaline earth metal.

4. The grease according to claim 1 wherein R contains from about 8 to about 22 carbon atoms.

5. The grease according to claim 1 wherein the said lubricating oil is a synthetic ester oil.

6. The grease according to claim 1 wherein the said lubricating oil is a synthetic ester oil represented by the formula wherein R is chosen from the group consisting of aliphatic hydrocarbon and aliphatic ether groups containing from 4 to 12 carbon atoms, R and R are aliphatic hydrocarbon groups containing from 1 to 12 carbon atoms and x is an integer from 1 to 5.

7. A lubricating grease consisting essentially of a lubricating oil thickened to a grease consistency with sodium p-(IJ-carbododecylon) aminobenzoate.

References Cited in the file of this patent UNITED STATES PATENTS 2,330,239 Prutton Sept. 28, 1943 2,628,974 Sanderson Feb. 17, 1953 2,852,466 Hotten Sept. 16, 1958 

1. A LUBRICATING GREASE CONSISTING ESSENTIALLY OF A LUBRICATING OIL THICKENED TO A GREASE CONSISTENCY WITH A COMPOUND REPRESENTED BY THE FORMULA 